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Miloš Sedlák - One of the best experts on this subject based on the ideXlab platform.
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enantiocatalytic activity of substituted 5 benzyl 2 pyridine 2 yl imidazolidine 4 one ligands
Tetrahedron-asymmetry, 2013Co-Authors: Pavel Drabina, Sergej Karel, Illia Panov, Miloš SedlákAbstract:Abstract Currently, asymmetric synthesis represents one of the main streams of organic synthesis. Although an extensive research has been carried out in this area, the synthesis of chiral compounds with the required enantiomeric purity is still a challenging issue. Herein, we focus on the preparation of new enantioselective catalysts based on pyridine-imidazolidinones. The substituted 5-benzyl-2-(pyridine-2-yl)imidazolidine-4-ones 5–8 were prepared by condensation of chiral amino acid amides (α-methylDOPA and α-methylphenylalanine) with 2-acetylpyridine and pyridine-2-carbaldehyde. The individual isomers of the described ligands 5 – 8 were separated chromatographically. The copper(II) complexes of these chiral ligands were studied as enantioselective catalysts for the asymmetric Henry reaction of substituted aldehydes with Nitromethane or nitroethane. The ligands containing a methyl group at the 2-position of the imidazolidinone ring 6a and 8a exhibit a high degree of enantioselectivity (up to 91% ee). The nitroaldols derived from nitroethane (2-nitropropan-1-ols) were obtained with a comparable enantiomeric purity to derivatives of 2-nitroethanol. This group of ligands represents a new and promising class of enantioselective catalysts, which deserve further attention.
Mariana Teodorescu - One of the best experts on this subject based on the ideXlab platform.
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calorimetric study of the selected nitroalkane chloroalkane binary systems
Journal of Thermal Analysis and Calorimetry, 2014Co-Authors: Mariana Teodorescu, Sara Maxia, Marianna Usula, Bruno Marongiu, Alessandra Piras, Silvia PorceddaAbstract:Excess enthalpies, HE, at 298.15 K and atmospheric pressure determined for 12 binary liquid mixtures containing Nitromethane or nitroethane+1-chlorobutane, +1-chloropentane, +1-chlorohexane, +1,2-dichloroethane, +1,3-dichloropropane, and +1,4-dichlorobutane by means of a flow 2277-LKB microcalorimeter, are reported on over composition range. The experimental results, along with the literature data on vapor–liquid equilibrium (VLE), excess Gibbs energies, GE, and activity coefficients at infinite dilution, \( \gamma_{\text{i}}^{\infty } \), are interpreted in terms of DISQUAC group contribution model. The systems are characterized by three types of contact surface: nitro (NO2), chlorine (Cl), and alkyl (CH3, CH2). The interchange energy parameters of the alkyl/NO2 and alkyl/Cl contacts were determined independently from the study of alkane+nitroalkane and alkane+chloroalkane systems. The structure-dependent interchange parameters of the NO2/Cl contact are reported in this work. The model provides a fairly consistent description of the VLE and of thermodynamic functions GE, HE, \( \gamma_{\text{i}}^{\infty } \), for all investigated mixtures.
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volumetric study for the binary Nitromethane with chloroalkane mixtures at temperatures in the range 298 15 to 318 15 k
Journal of Chemical & Engineering Data, 2013Co-Authors: Daniela Gheorghe, Dana Dragoescu, Mariana TeodorescuAbstract:The results of the density measurements for the pair systems containing Nitromethane with 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, chloroform, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1-chlorobutane, and 1-chloropentane at T = (298.15, 308.15, and 318.15) K and atmospheric pressure on entire compositional range are reported. The derived excess molar volumes, VE, are positive for the Nitromethane + 1,1,1-trichloroethane, + 1,2-dichloroethane, + 1,3-dichloropropane, + 1,4-dichlorobutane, + 1-chlorobutane, and + 1-chloropentane binary mixtures, and they are negative for the other two systems: Nitromethane + 1,1,2,2-tetrachloroethane, and + chloroform, on the entire compositional range and at all three studied temperatures. The excess molar volumes have been correlated with the three-parameter Redlich–Kister equation.
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isothermal vapor liquid equilibria and excess gibbs free energies in some binary nitroalkane chloroalkane mixtures at temperatures from 298 15k to 318 15k
Fluid Phase Equilibria, 2013Co-Authors: Dana Dragoescu, Mariana Teodorescu, Daniela GheorgheAbstract:Abstract The vapor pressures of binary mixtures of cloroalkane (1-chlorobutane, 1-chloropentane) + Nitromethane or nitroethane were measured at temperatures between 298.15 K and 318.15 K. The vapor pressures vs. liquid phase composition data have been used to calculate the activity coefficients of the two components, and the excess molar Gibbs energies GE for the mixtures, using Barker's method. Redlich–Kister, Wilson, NRTL and UNIQUAC equations, taking into account the vapor phase imperfection in terms of the 2-nd virial coefficient, have represented the GE values. No significant difference between GE values obtained with these equations has been observed. The results indicate that all the systems show positive deviations from Raoult's law. The experimental VLE data were analyzed in terms of the modified UNIFAC (Dortmund) model.
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isothermal vapour liquid equilibria for Nitromethane or nitroethane 1 4 dichlorobutane binary systems at temperatures between 343 15 and 363 15 k
The Journal of Chemical Thermodynamics, 2013Co-Authors: Mariana Teodorescu, Dana Dragoescu, Daniela GheorgheAbstract:Isothermal vapor–liquid equilibrium (VLE) data are reported at three temperatures, (343.15, 353.15, and 363.15) K, for the binary mixtures containing Nitromethane or nitroethane with 1,3-dichloropropane. For the measurements an all-glass ebulliometer was used, which allows sampling from both phases in equilibrium. The experimental data were correlated using the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) excess Gibbs energy models by means of maximum likelihood method, taking into account the vapor phase imperfection in terms of the second virial coefficients. Both systems are azeotropic and show positive deviations from ideal behavior. The experimental VLE data are analyzed in terms of the modified UNIFAC (Do) model.
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isothermal vapour liquid equilibria for 1 2 dichloroethane Nitromethane and nitroethane binary systems at temperatures between 333 15 and 353 15k
Fluid Phase Equilibria, 2010Co-Authors: Mariana Teodorescu, Alexandru Barhala, Dana DragoescuAbstract:Abstract Isothermal vapour–liquid equilibrium (VLE) data are reported at three temperatures, 333.15, 343.15 and 353.15 K, for binary mixtures containing 1,2-dichloroethane with Nitromethane or nitroethane. Use has been made of an ebulliometer which allows sampling from both phases in equilibrium. The experimental data were correlated using the Redlich–Kister, Wilson, NRTL and UNIQUAC excess Gibbs energy models by means of the maximum likelihood method, taking into account the vapour phase imperfection in terms of the second virial coefficients. Both systems are zeotropic and show positive deviations from ideal behaviour. The experimental VLE data are analysed in terms of the Modified UNIFAC (Do) model.
Dana Dragoescu - One of the best experts on this subject based on the ideXlab platform.
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volumetric study for the binary Nitromethane with chloroalkane mixtures at temperatures in the range 298 15 to 318 15 k
Journal of Chemical & Engineering Data, 2013Co-Authors: Daniela Gheorghe, Dana Dragoescu, Mariana TeodorescuAbstract:The results of the density measurements for the pair systems containing Nitromethane with 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, chloroform, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1-chlorobutane, and 1-chloropentane at T = (298.15, 308.15, and 318.15) K and atmospheric pressure on entire compositional range are reported. The derived excess molar volumes, VE, are positive for the Nitromethane + 1,1,1-trichloroethane, + 1,2-dichloroethane, + 1,3-dichloropropane, + 1,4-dichlorobutane, + 1-chlorobutane, and + 1-chloropentane binary mixtures, and they are negative for the other two systems: Nitromethane + 1,1,2,2-tetrachloroethane, and + chloroform, on the entire compositional range and at all three studied temperatures. The excess molar volumes have been correlated with the three-parameter Redlich–Kister equation.
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isothermal vapor liquid equilibria and excess gibbs free energies in some binary nitroalkane chloroalkane mixtures at temperatures from 298 15k to 318 15k
Fluid Phase Equilibria, 2013Co-Authors: Dana Dragoescu, Mariana Teodorescu, Daniela GheorgheAbstract:Abstract The vapor pressures of binary mixtures of cloroalkane (1-chlorobutane, 1-chloropentane) + Nitromethane or nitroethane were measured at temperatures between 298.15 K and 318.15 K. The vapor pressures vs. liquid phase composition data have been used to calculate the activity coefficients of the two components, and the excess molar Gibbs energies GE for the mixtures, using Barker's method. Redlich–Kister, Wilson, NRTL and UNIQUAC equations, taking into account the vapor phase imperfection in terms of the 2-nd virial coefficient, have represented the GE values. No significant difference between GE values obtained with these equations has been observed. The results indicate that all the systems show positive deviations from Raoult's law. The experimental VLE data were analyzed in terms of the modified UNIFAC (Dortmund) model.
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isothermal vapour liquid equilibria for Nitromethane or nitroethane 1 4 dichlorobutane binary systems at temperatures between 343 15 and 363 15 k
The Journal of Chemical Thermodynamics, 2013Co-Authors: Mariana Teodorescu, Dana Dragoescu, Daniela GheorgheAbstract:Isothermal vapor–liquid equilibrium (VLE) data are reported at three temperatures, (343.15, 353.15, and 363.15) K, for the binary mixtures containing Nitromethane or nitroethane with 1,3-dichloropropane. For the measurements an all-glass ebulliometer was used, which allows sampling from both phases in equilibrium. The experimental data were correlated using the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) excess Gibbs energy models by means of maximum likelihood method, taking into account the vapor phase imperfection in terms of the second virial coefficients. Both systems are azeotropic and show positive deviations from ideal behavior. The experimental VLE data are analyzed in terms of the modified UNIFAC (Do) model.
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isothermal vapour liquid equilibria for 1 2 dichloroethane Nitromethane and nitroethane binary systems at temperatures between 333 15 and 353 15k
Fluid Phase Equilibria, 2010Co-Authors: Mariana Teodorescu, Alexandru Barhala, Dana DragoescuAbstract:Abstract Isothermal vapour–liquid equilibrium (VLE) data are reported at three temperatures, 333.15, 343.15 and 353.15 K, for binary mixtures containing 1,2-dichloroethane with Nitromethane or nitroethane. Use has been made of an ebulliometer which allows sampling from both phases in equilibrium. The experimental data were correlated using the Redlich–Kister, Wilson, NRTL and UNIQUAC excess Gibbs energy models by means of the maximum likelihood method, taking into account the vapour phase imperfection in terms of the second virial coefficients. Both systems are zeotropic and show positive deviations from ideal behaviour. The experimental VLE data are analysed in terms of the Modified UNIFAC (Do) model.
Hong-min Liu - One of the best experts on this subject based on the ideXlab platform.
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the henry reaction of 1r 1 4 3 6 dianhydro d mannitol 2 yl 1 4 3 6 dianhydro d fructose 5 5 dinitrate different reactive features of Nitromethane to nitroethane
Carbohydrate Research, 2009Co-Authors: Feng-wu Liu, Zhen-ji Wang, Xiao-ping Song, Sai-yang Zhang, Hong-min LiuAbstract:Henry reactions of a novel higher sugar derivative, (1R)-(1,4:3,6-dianhydro-D-mannitol-2-yl)-1,4:3,6-dianhydro-D-fructose 5,5'-dinitrate (Alternate nomenclature: (1R)-(isomannid-2-yl)-1,4:3,6-dianhydro-D-fructose 5,5'-dinitrate), with Nitromethane and nitroethane were studied. The kinetic and thermodynamic reactions with Nitromethane under different conditions were carried out to afford (2S)- and (2R)-beta-nitroalcohols, respectively. But when using nitroethane the reaction gave a (2S)-beta-nitroalcohol with an inverted configuration at vicinal carbon C-1. Two stereogenic centers were generated, and one was altered in the reaction.
Daniela Gheorghe - One of the best experts on this subject based on the ideXlab platform.
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volumetric study for the binary Nitromethane with chloroalkane mixtures at temperatures in the range 298 15 to 318 15 k
Journal of Chemical & Engineering Data, 2013Co-Authors: Daniela Gheorghe, Dana Dragoescu, Mariana TeodorescuAbstract:The results of the density measurements for the pair systems containing Nitromethane with 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, chloroform, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, 1-chlorobutane, and 1-chloropentane at T = (298.15, 308.15, and 318.15) K and atmospheric pressure on entire compositional range are reported. The derived excess molar volumes, VE, are positive for the Nitromethane + 1,1,1-trichloroethane, + 1,2-dichloroethane, + 1,3-dichloropropane, + 1,4-dichlorobutane, + 1-chlorobutane, and + 1-chloropentane binary mixtures, and they are negative for the other two systems: Nitromethane + 1,1,2,2-tetrachloroethane, and + chloroform, on the entire compositional range and at all three studied temperatures. The excess molar volumes have been correlated with the three-parameter Redlich–Kister equation.
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isothermal vapor liquid equilibria and excess gibbs free energies in some binary nitroalkane chloroalkane mixtures at temperatures from 298 15k to 318 15k
Fluid Phase Equilibria, 2013Co-Authors: Dana Dragoescu, Mariana Teodorescu, Daniela GheorgheAbstract:Abstract The vapor pressures of binary mixtures of cloroalkane (1-chlorobutane, 1-chloropentane) + Nitromethane or nitroethane were measured at temperatures between 298.15 K and 318.15 K. The vapor pressures vs. liquid phase composition data have been used to calculate the activity coefficients of the two components, and the excess molar Gibbs energies GE for the mixtures, using Barker's method. Redlich–Kister, Wilson, NRTL and UNIQUAC equations, taking into account the vapor phase imperfection in terms of the 2-nd virial coefficient, have represented the GE values. No significant difference between GE values obtained with these equations has been observed. The results indicate that all the systems show positive deviations from Raoult's law. The experimental VLE data were analyzed in terms of the modified UNIFAC (Dortmund) model.
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isothermal vapour liquid equilibria for Nitromethane or nitroethane 1 4 dichlorobutane binary systems at temperatures between 343 15 and 363 15 k
The Journal of Chemical Thermodynamics, 2013Co-Authors: Mariana Teodorescu, Dana Dragoescu, Daniela GheorgheAbstract:Isothermal vapor–liquid equilibrium (VLE) data are reported at three temperatures, (343.15, 353.15, and 363.15) K, for the binary mixtures containing Nitromethane or nitroethane with 1,3-dichloropropane. For the measurements an all-glass ebulliometer was used, which allows sampling from both phases in equilibrium. The experimental data were correlated using the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) excess Gibbs energy models by means of maximum likelihood method, taking into account the vapor phase imperfection in terms of the second virial coefficients. Both systems are azeotropic and show positive deviations from ideal behavior. The experimental VLE data are analyzed in terms of the modified UNIFAC (Do) model.
